This section is intended to introduce the reader to various aspects of art that may be related to aspects of the presented inventions which are described and/or claimed below. This section is believed to be helpful in providing the reader with background information to help understand the various aspects of the present invention. Accordingly, it should be understood that the statements in this section are to be read in this light, and not as admissions of prior art.
In a number of applications where materials are sprayed onto a surface, two or more components are mixed immediately prior to their application to the surface. In these applications, the components typically begin reacting upon their combination in a mixing line or mixing chamber and cure once applied to a surface. Such ‘multi-component’ mixtures are utilized for varying applications. In many of these multi-component applications, precise control of the mixing ratio of the individual components is important to provide a final product having desired qualities.
One exemplary application where controlling the mixing ratio of a multi-component mixture is important is the roadway-marking industry. In this application, incorrect ratios of material components adversely affect the set times and durability of the final roadway-marking lines. Such inferior lines have a reduced life span and fade over time. Manual roadway-marking mixture control systems currently exist to help control the ratio of multi-component mixtures. However, manual methods without real time feedback typically fail to provide timely and accurate data regarding actual flow output rates and, hence, mixing ratios of pumps supplying individual components to a mixing line/chamber—leading to inconsistent marking lines. Moreover, typical control systems are manually adjusted based on pump speed setting alone rather than actual flow rates and pump output.
Often, pump speed settings are not an accurate representation of flow. Independent of pump speed settings, the actual flow output rates from the pumps that affect mixing ratios may vary due to changes in temperature, pressure, and viscosity of the components. That is, manual systems that set mixing ratios by merely increasing and decreasing pump speeds without accounting for actual output flow rates of the component supply pumps generally fail to provide consistent mixing ratios as the temperature, pressure, and viscosity of the mixing materials change over time. In addition, existing systems typically change mixing ratios by only altering the pump speed of a secondary component pump—not accounting for actual flow changes in primary component pumps. In the case of hydraulically controlled pumps, the pump speed of primary and secondary pumps are controlled by adjusting hydraulic pressure to the pumps. However, such hydraulic pressure is not directly related to material flow change due to the nature of hydraulics. Accordingly, there is a need for a control system that can automatically and timely adjust mixing ratios based on accurate flow rates and pump speeds to provide consistent final products.